Unit 6: Molecular Genetics Flashcards
What does DNA stand for
Deoxyribose nucleic acid
What does RNA stand for
Ribose nucleic acid
What are the 3 components of a DNA monomer
Nitrogenous Base (A,T,G,C), Sugar, Phosphate
What type of bond links nitrogenous base
Hydrogen Bonds
How many hydrogen bonds link A and T/U
2
How many hydrogen bonds link together G and C
3
On what molecule of DNA is 5’ end always on
Phosphate
DNA strands run Antiparallel
On what molecule of DNA is 3’ end always on
The OH of Phosphate
DNA strands run Antiparallel
Overall purpose of DNA
Contains coded information that programs all cell activity
Overall purpose of RNA
Functions in the actual synthesis of proteins coded by DNA
State 3 differences between prokaryotes and eukaryotes
Circular DNA : Linear DNA
Replication occurs in cytoplasm : Replication occurs in nucleus
No histones : DNA wrapped around histones
Supercoiled DNA : Forms Chromatin
What is the political beliefs of DNA
Semi-conservative - Daughter DNA molecules each consist of one parental strand and one new strand
Determined by Meselson and Stahl
What end is the Leading strand
5’
What is the function of the helicase
To unzip the parental strand
When is DNA replicated
for mitosis or meiosis
The ___ strand is synthesized continuously by __________
Leading Strand/5’; DNA Polymerase
On the Lagging strand, Primase places a RNA primer in which DNA polymerase begins to synthesize an _____ from the ___’ end to the ___’ end
okazaki fragment: 3’; 5’
What is the function of DNA Ligase
To join the Okazaki fragment with the growing strand
What is the function of the Topoisomerase
To relax the supercoiled DNA and unwind it so the Helicase can unzip it.
What are the main steps of gene expression
DNA–> RNA using Transcription
Introns are cut out by Spliceosomes, creates mRNA
End caps are put on and mRNA is exported out of the nucleus
mRNA is the Translated to create an amino acid chain
DNA–>RNA–>mRNA–>Protein
What is a mRNA triplet also called?
Codon
What direction does RNA polymerase read in and on what strand?
From 3’ to 5’ on the non-coding strand
What reads mRNA in the cytoplasm?
A ribosome
What are the binding sites on the ribosome during translation
E,P,A
What molecule brings matching codons and amino acid to the binding site?
tRNA
The binding site ___ forms a ___ that will later make a protein
P; amino acid chain
The binding site ___ forms a ___ with the binding site __ to add to the __ chain
P; peptide bond; A; amino acid/polypeptide
What happens to the protein after translation?
Assume it is leaving the cell
It goes to the Golgi complex where it is prepared for use out of the cell, is transported via vesicle to the cell membreane and then undergos exocytosis
Describe a point mutation
One nucleotide error, substitutions
Ex. A instead of G
Describe a Frameshift Mutation
One or more base is deleted or inserted
May alter reading frame –> disastrous effect on resulting protein
Missense Mutation vs Nonsense Mutation
Missense still codes for an amino, just not the correct one; Nonsense changes amino acid codon into a stop codon - leads to a nonfunctional protein
What are some Large-Scale Mutations and where did their errors occur?
Deletion - loss of a chromosomal segment - Replication
Duplication - repetition of a segment - Replication
Inversion - reverses a segment - Crossing Over
Translocation - Moves segment from one chromosome to a non-homologous chromosome - Crossing over
What are the 4 steps of translation and their function?
Initiation - Start codon binds to ribosome, tRNA carrying Met attatches to P site, lage subunit attatches
Elongation - consists of codon recognition and peptide bond formation
Translocation - tRNAs shift over a site
Termination - Polypeptide release
What are the 2 types of operons in prokaryotic regulation and what do they mean?
Inducible: a lac operon binds to the repressor presend and allows the gene to be expressed (off until bound)
Repressible: Corepresessor binds to the repressor to prohibit gene expression (on until bound)
How do eukaryotes use gene regulation?
Transcription factors bind too DNA sequences and other regulatory regions (both + and -)
How do viruses enter the cell and what do they do?
Bacteriophages inject viral DNA into host cell, replicates and manufactures capsid proteins in order to assemble new virus and exit cell
